The present invention pertains to improvements in power operated wrenches which have a drive mechanism which intermittently rotates a wrench socket or the like. Such tools are also commonly known as ratchet wrenches.
Prior art power ratchet wrench drive mechanisms are known in which a rotary cam actuates a push rod by means of an intermediate member such as a roller or the like. A mechanism which is popular is generally of the type disclosed in U.S. Pat. No. 2,119,968. However, it has been determined that certain improvements are desirable in power rachet wrenches which will increase the useful life of the wrench mechanism and reduce the manufacturing cost thereof. For example, prior art drive mechanisms of the general type referred to hereinabove develop damaging lateral forces due to the arrangement of the cam, cam follower, and push rod return spring. Moreover, the roller type cam follower is subject to wear as is the rotary cam surface due to lateral movement of the push rod during operation. Furthermore, many prior art ratchet wrench mechanisms are not easily lubricated sufficiently to reduce wear and friction which is otherwise likely to contribute to early mechanism failure.